Association between habitual physical activity and brown adipose tissue activity in individuals undergoing PET-CT...

Augmented brown adipose tissue (BAT) mass and activity lead to higher basic metabolic rate which is beneficial against obesity. Our aim was to investigate whether habitual (i.e. usual weekly participation) physical activity is linked with BAT activity and mass in humans, in a group of patients undergoing (18) F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) scanning.

Cross-sectional study.

Forty patients with cancer [26 male; 14 female; age 52·7 ± 17·5; body mass index (BMI) 26·4 ± 4·5].

Patients completed the 'usual week' form of the International Physical Activity Questionnaire and underwent assessment of BAT activity/mass via (18) F-fluorodeoxyglucose PET/CT.

We detected a significant association between habitual physical activity (METs-minute/week) and BAT activity [normalized by body weight (BW) (τ = 0·28, P = 0·02), body surface area (BSA) (τ = 0·29, P = 0·02) and lean body mass (LBM) (τ = 0·38, P = 0·002)]. We also found a significant negative relationship between BMI and BAT activity [normalized by BW (τ = -0·30, P = 0·006), BSA (τ = -0·31, P = 0·004) and LBM (τ = -0·45, P = 0·001)] as well as a significant negative relationship between age and BAT activity [normalized by LBM (τ = -0·28, P = 0·01)]. The results also indicate significant differences between low/moderate/high levels of habitual physical activity and BAT activity (P < 0·05). Moreover, BAT activity was different across the BMI categories (normal/overweight/obese) in both sexes (P < 0·05). Finally, BAT activity was greater in women than in men (P < 0·05).

Increased participation in habitual physical activity is associated with higher BAT activity. Moreover, individuals with normal BMI demonstrate higher BAT activity compared to overweight and obese individuals. Finally, age is inversely linked with BAT activity, while women demonstrate higher BAT activity than men.